permaculture

[KAKerby@aol.com]

The question of what to use for media is one of the most hotly debated  
(usually in friendly ways) topics in hydro- and aquaponics at the moment.   
There's a breathtaking array of possibilities, ranging from good old 
fashioned  
sand, to gravel, to lava rock, even peat moss, coir and other natural  
materials.  How those materials are gathered, refined and  sold will in part 
determine whether folks want to use them for that  purpose.  Clean beach sand 
is one thing; gravel gathered from the  side of a busy road, probably not.  
Of course there's also the man-made  materials, with perlite/vermiculite 
being a popular combo, expanded clay pellets  being popular and easy to work 
with but expensive, and goodness knows what's  come out in the last few years 
that I haven't kept up with.  Each one of  them has their pro's and con's, 
and each one of them ranks differently in terms  of cradle-to-grave analysis. 
 
None of them are the clear hands-down winner,  usually because folks come 
into this activity from lots of different  backgrounds, with different needs 
and access to different materials.  What  works for some family in 
sub-Saharan Africa won't be the same "good answer" for  someone trying to 
garden on 
the roof of some high-rise in Hong Kong.
 
One of the really interesting developments in recent years is the addition  
of earthworms to the mix.  That is also hotly contested where some folks  
claim it's not necessary or even beneficial, while others swear their systems 
 won't run without it.  There is a lot to be said for worm castings, and 
the  worms keep the system very nicely cleaned of any biological buildup 
which 
 otherwise wouldn't have a purpose and becomes a maintenance issue.  My  
"take" on it is that such buildup is an "output" begging to become an 
"input", 
 and worms are a nice way to do that.  But those populations do need to be  
balanced within an ever-more-complex system, and that takes more effort.   
Furthermore, some folks wonder if the aquaponics should then be called  
"vermiponics" and well, I guess that could be argued either way.  
 
What I find fascinating is that at the end of the day, both "soil-based"  
and "soilless-based" ag forms are moving towards each other and becoming 
nearly  indistinguishable over the passage of time.  Totally organic (ie,  
carbon-based) systems, such as peat-moss or coir-based media systems 
eventually  
need powdered rock and/or other mineral, inorganic inputs to stay  balanced. 
 Totally inorganic, inert media systems like gravel and sand need  living 
components in the media, such as worms, to cycle everything.  Almost  
regardless of what folks start off with, give the system enough time and  
"nudges" 
towards overall system balance, and you end up with material that is  quite 
similar to soil.  Because that's what soil is - a combination of  living and 
mineral materials that have co-existed for many generations.  At  which 
point most of the objections to aquaponics sort of fade into the  background 
as 
"maybe was a concern once, but not anymore."  The fact that  folks can 
arrive at edible food and low-input meats this way, when they might be  18 
stories up in some metroplex, or in the middle of a desert, is the part I  
find 
so very appealing.  It really is food production for anyone who wants  it, 
regardless of where they're living.  So in my mind and in my little  personal 
definition of permaculture, aquaponics is as valid an approach as any  
other.  
Kathryn Kerby
frogchorusfarm.com
Snohomish, WA USA
 
 
In a message dated 10/8/2012 9:45:08 A.M. Pacific Daylight Time,  
venaurafarm@bellsouth.net writes:

On  10/8/2012 11:28 AM, Toby Hemenway wrote:

> plants. It contains N  primarily in the form of ammonia, and the usual
> bacteria are present  in the gravel beds (which are best made with
> lava rock or some other  high-edge substance) to convert it to nitrite
> and  nitrate.

Could biochar be used as a component, along with gravel or  lava rock  in 
the growing medium? It seems like a perfect ingredient,  absorbs toxins, 
retains nutrients.

Lava rock has a very high carbon  footprint and may contain toxins: it is 
sometimes manufactured in kilns  fired with toxic petrochemical waste or 
by products or flammable  industrial waste - or so I hear - maybe this 
has changed. Mine the rock to  be converted to lava rock, fire it, store 
and ship it in bulk or bagged.  High carbon  footprint.

LL
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